Summary Antiretroviral therapy (ART) has significantly reduced HIV-related morbidity and mortality. However, therapeutic life expectancy for individuals with HIV increased, the long-term safety of ART has gained increasing attention. Thus, it is highly important to the long-term safety of antiretroviral regimens. Human hepatocyte cell lines in 2D culture are most used to evaluate short-term mitochondrial toxicity (MtT) induced by ART. However, these cannot be used in detection of ART-induced chronic MtT because they cannot survive more than days during toxicity testing. In addition, antiviral drug toxicity screening often requires expensive primary such as peripheral blood monocytes in 2D culture systems. More than 90% of drugs that pass through in 2D culture preclinical studies fail to meet the desired efficacy or safety margins required in subsequent trials. Clearly, 2D cultures have contributed to the poor predictive power of MtT screening assays in . Although long-term toxicity tests are often performed in animal models, the high rates of MtT observed in earlier clinical trials suggest that animal toxicology studies may not be suitable for predicting MtT of antiviral intended for human use. Apparently, there are no adequate 2D cell culture or animal models for late MtT for preclinical drug development. Hence, there is an urgent need to develop more toxicologically and clinically predictive in vitro assays to assess compounds for the potential of late MtT. We were the to demonstrate that stem/progenitor cells exist in human urine, i.e., urine-derived stem cells (USC). These can be obtained using simple, non-invasive and low-cost procedures. USC express telomerase activity possess robust proliferative potential. We recently revealed that 3D culture of USC provides a long-term, microenvironmen for cell growth and proliferation, mimicking in vivo conditions, which may have to improve the predictive outcome of preclinical antiviral drug studies. Thus, is to develop 3D culture systems of human USC for ART-induced MtT testing. We hypothesize that human USC maintain telomerase activity and mitochondrial function in 3D organoids, which considerably extends the life of cell culture systems, enabling long-term assessment of late ART-induced MtT . To test this hypothesis, we propose the following: Aim 1. Assess the stemness properties and mitochondrial function of human USC in 3D organoids over long-term culture, compared to 2D culture of USC; Aim 2. Determine the cytotoxicity, inhibition of Pol-?, mitochondrial DNA content and MtT profiles of 9 antiretroviral drugs in 3D USC cultures. We that the antiretroviral drugs tested will exhibit effects on MtT in the 3D culture systems and be ranked to their effective concentrations based on in vitro MtT assay. Therefore, the use of patients-derived cells from urine to generate 3D culture assay offers a promising tool for antiretroviral drug development personalized medicine in the assessment of MtT of anti-HIV drugs. benefit of ART is often limited by delayed drug-associated toxicity. As has monitor commonly hepatocytes 14 cells vitro clinical vitro the drugs evaluation relevant first cells and better t potential the goal of this project anticipate according stem and